Summary of Significant Accounting Policies - Additional Information (Detail) £ in Millions		12 Months Ended
	Jul. 09, 2014	Dec. 31, 2015 USD ($) Segment	Dec. 31, 2015 GBP (£)	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Stockholders' equity, stock split conversion ratio	0.7692
Stock conversion ratio		Nine-for-one basis
Number of reportable segments | Segment		1
Number of operating segments | Segment		1
Accumulated deficit | $		$ 98,110,000		$ 40,889,000
Foreign currency value held | £			£ 1.5
Cash and cash equivalents maturity period		90 days
Investment maturity period		90 days
Impairment of long-lived assets | $		$ 0
Expected dividend yield		0.00%
Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		3 years
Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		5 years